Conventionally, a liquid-cooled heat sink is known to have two plates that have a plate shape and are liquid-tightly brazed with each other on a condition of being coupled face to face. The liquid-cooled heat sink therein houses a herringbone type fin configured by vertical ribs, and tip portions of the vertical ribs are bent such that a flow rate of a cooling liquid flowing in each portion of the fin becomes uniform (refer to Patent Literature 1 etc.).